Cardiac development results from a variety of regulatory processes. The HCCB Research Ctr is focused on defining one of these processes-the transcriptional regulatory network. Regulation of RNA transcription is recognized to play critical roles in developmental processes, definition of the entire repertoire of transcriptional regulators and their interactions during cardiac embryogenesis remains largely unknown. While large numbers of transcription factors have been identified that are involved in cardiac development the processes that activate these transcription factors and the downstream targets of these transcription factors are not known. We propose to employ novel genomic and genetic methods to define the network of transcription factors that regulate multiple steps in cardiac development and overlay that network on the RNA expression profile found in these developing tissues. In the end this should provide an RNA blueprint for understanding cardiac development. Definition of the network required for cardiac development would enhance understandings of the roles of recently discovered post-transcriptional regulatory mechanisms (e.g. microRNAs) that may modify developmental processes. We will take advantage of novel technologies to define the RNA expression networks, including both temporal and spatial patterns of gene expression that formation of primary and secondary heart fields to adult chamber formation. Three different novel technologies will be employed to define RNA profiles in each tissue at critical stages of development (DSAGE and RNAseq) and to identify likely downstream targets of particular transcription factors (bioCHIP). DSAGE and RNAseq employ high throughput DNA sequencing technologies to define the structure and level of RNA expression, while bioCHIP defines the promoter sites within the genome that are bound by particular transcription factors. Together this information will define transcription factor levels and their downstream target genes. Molecules that are identified as central for developmental steps will be validated by perturbation experiments, including molecular and phenotypic analyses. Together with data from human studies, we will construct a cardiac developmental blueprint and interrogate how perturbations of this blueprint result in congenital heart disease. 1) Define the transcriptome in the primary heart field, the secondary heart field and in developing cardiac chambers using DSAGE and RNAseq. 2) Identify binding targets of GATA4, F0G2, TBX5, NKX2.5 and other transcription factors critical for cardiac development using DCHIP. 3) Construct a developmental blueprint for developmental stages of cardiac specification and morphogenesis from .model organism and human datasets. 4) Validate crifical role of defines nodes in the blueprint by perturbing RNA levels and defining molecular and phenotypic consequences. RELEVANCE (See instructions): The goal of the proposed research is to define transcriptional networks that lead to formation of the mature heart. Defining this network will provide novel insights into the pathogenesis of a variety of congenital heart diseases (CHD). Eventually such studies may allow new therapeutic approaches to CHD.